A battery module is formed by stacking a plurality of battery cells. A battery pack is formed by combining the battery module with a control panel, etc. For example, a battery cell (which is a secondary battery) comprises an outer case, a nonaqueous electrolyte contained in the case, and an electrode member. It is known that a battery cell used repeatedly expands at the end of its battery life because the gas generated inside increases the internal pressure. In a battery module including such an expanded battery cell, the adjacent cells may separate from each other, causing damage to the battery cells. In addition, the electrode member may also separate from the case, resulting in the deterioration of battery performance.
To solve the problems, a method of using a band in the stacking direction of battery cells is known in the art. The band serves to immovably hold the battery cells and to suppress the expansion of the battery cells. However, the use of this method does not completely suppress the expansion of the battery cells because the band is soft and flexible.
Accordingly, the embodiments are intended to provide a battery module which prevents the expansion of a battery cell and the separation of an electrode member, prevents the adjacent battery cells from being displaced from each other at the time of assembly of the battery module, and which can be assembled with ease.